Zheng Ting, Lin Yu-Chuan, Rafizadeh Neema, Geohegan David B, Ni Zhenhua, Xiao Kai, Zhao Hui
School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China.
Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, United States.
ACS Nano. 2022 Mar 22;16(3):4197-4205. doi: 10.1021/acsnano.1c10082. Epub 2022 Mar 2.
Charge transfer properties of van der Waals heterostructures formed by Janus and regular transition metal dichalcogenide monolayers are studied by time-resolved pump-probe measurements and photoluminescence spectroscopy. Measurements of electron and hole transfer in three heterostructures with atomic layer sequences of S-W-Se/S-W-S, Se-W-S/S-W-S, and S-W-Se/Se-W-Se reveal that charge transfer from regular to Janus monolayers is ultrafast regardless of the direction of the built-in electric field of the Janus monolayer (Janus field). However, the charge transfer from Janus to regular layers is directional and controlled by the Janus field. When the current direction is along the field, the charge transfer is ultrafast and efficient, while the field blocks the charge transfer with an opposite charge current direction. The transferred carriers form interlayer excitons with extended lifetimes compared to the intralayer excitons. The demonstrated ultrafast and directional charge transfer between Janus and regular TMD layers shows that the Janus structures can be used to make 2D heterostructures with efficient and directional charge transfer properties.
通过时间分辨泵浦-探测测量和光致发光光谱研究了由Janus和常规过渡金属二硫属化物单层形成的范德华异质结构的电荷转移特性。对具有S-W-Se/S-W-S、Se-W-S/S-W-S和S-W-Se/Se-W-Se原子层序列的三种异质结构中的电子和空穴转移测量表明，无论Janus单层（Janus场）的内建电场方向如何，从常规单层到Janus单层的电荷转移都是超快的。然而，从Janus层到常规层的电荷转移是有方向的，并受Janus场控制。当电流方向沿场方向时，电荷转移是超快且高效的，而场会阻止相反电荷电流方向的电荷转移。与层内激子相比，转移的载流子形成具有更长寿命的层间激子。Janus层和常规TMD层之间超快且有方向的电荷转移表明，Janus结构可用于制造具有高效和有方向电荷转移特性的二维异质结构。
